"use strict";
{
    let str = '123';
    let result = [{ username: 'xx', password: 'xxx' }, { username: 'yyy', password: 'zzz' }];
    let b = {
        id: 10,
        title: '郭敬明',
        price: 15.9
    };
    //获取接口键名的联合类型  key 键  of 属于 
    // type keys = keyof User;             'username' | 'password'
    function getUserValue(obj, key) {
        return obj[key];
    }
    let user = {
        username: 'xxx',
        password: 'xxx',
        email: 'xxxx'
    };
    getUserValue(user, 'username');
    //声明一个函数
    function test(a, b) {
        return a + b;
    }
    let t;
}
